The OnWrite event is generated for non-blocking sockets
when data can be written to the server after a previous attempt
failed because it would cause the control to block. This event is
only generated for asynchronous sockets when the Blocking
property is set to False.
This event will always be generated at least one time, after the
connection to the server is initially established. It will not
fire again unless the Write method fails with the error
swErrorOperationWouldBlock, which indicates that the socket's
send buffer is full. When the socket can accept more data, this event
will fire and the application can resume sending data to the remote
host.